Segments and Disaggregated Revenue (Narrative) (Details) $ in Millions	3 Months Ended
	Apr. 30, 2020 USD ($) segment	Apr. 30, 2019 USD ($)
Revenue from External Customer [Line Items]
Number of reportable segments | segment	3
Net sales	$ 133,672	$ 122,949
Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	88,743	80,344
Walmart International
Revenue from External Customer [Line Items]
Net sales	29,766	28,775
Sam's Club
Revenue from External Customer [Line Items]
Net sales	15,163	13,830
eCommerceMember | Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	8,300	4,700
eCommerceMember | Walmart International
Revenue from External Customer [Line Items]
Net sales	2,900	2,500
eCommerceMember | Sam's Club
Revenue from External Customer [Line Items]
Net sales	$ 1,000	$ 700